OP here. I'm open to the idea that some of these battles are just me being me. So far my experience has been.. inconsistent to say the least.
For example, the first co-OP battle just popped up for me. It's a single fight against Jade, and you can either let the game find a partner for you, invite someone yourself to a private tag match, or go solo. I couldn't get anyone else so I went in solo and beat her on my second attempt.
Then a few towers later I come across the Kollector as a boss, with 2 assists- Rains bubble, and Blood red vampire bats. The rain bubble seemingly appears below your feet every 10 or so seconds and can be blocked. The bats fly horizontally across the screen in packs of 3. There is a gap between the first bat and the other 2. So if you get hit by the first, you can still block the next 2. For each bat that hits you, you take damage and the opponent recovers HP.
This fight took me about 10 tries before I decided to use a consumable. The AI is coded to anti air me half the time as soon as I leave the ground. And the Kollector does boosted damage in this fight. However, I found one of the best consumables for a hit sponge boss like this - Nitaras rain that takes 3 slots and lasts forever. It does damage over time to the enemy and leaves a puddle on the ground, standing on which recovers HP. Also, it goes off cooldown every 30 seconds and stacks! So it was an epic battle of attrition with the kollector that lasted 200 seconds but I came out on top.
I'm still in the process of beating Noobs second character tower so no updates there. To even attempt the final 2 towers, I have to get 75 fatalities and 75 brutalities done as noob, and I'm only on 30, and 5 respectively.
Regarding the Krypt, I am not aware if its randomized, but based on its design I can say that certainly there are items that are randomized but big, key unlocks might be the same for everyone?
I dont want anyone to come out of this thread regretting their purchase. Look at the silver lining, you could still be playing this game 2 years from today and still unlocking new things. I would say this is bad news to anyone who wanted to unlock everything for their character in the first month, which is an unrealistic expectation in my opinion.